离线查询上的 React-native-firebase 服务器时间戳

Question

I'm trying to query with a where condition on a server timestamp field, work's perfectly, but when it's offline the snapshot do not trigger until it's online again. When I remove the where condition works fine.

Is it possible to work offline with this server timestamp field? Or am I doing something wrong?

here's my query:

firestore()
  .collectionGroup(collectionNames.MESSAGES)
  .where('chatId', 'in', chatIds)
  .where('updatedAt', '>', lastMessageDate)
  .onSnapshot({ includeMetadataChanges: true }, onMessage, onError)

and here's my object:

create({ chatId, type, text, url, user }) {
  const { id, email, name, avatarUrl } = user
    this.chatId = chatId
    this.type = type
    this.text = text
    this.url = url
    this.ownerId = id
    this.ownerEmail = email
    this.ownerName = name
    this.ownerAvatarUrl = avatarUrl
    this.updatedAt = firestore.FieldValue.serverTimestamp()
    return this.toJSON()
}

Answer 1

firestore.FieldValue.serverTimestamp() is evaluated server side so you will not be able to use it offline. Here is a good article https://medium.com/firebase-developers/the-secrets-of-firestore-fieldvalue-servertimestamp-revealed-29dd7a38a82b

Answer 2

Since server timestamps are evaluated on the server, they don't have an actual value until the document finally gets synchronized. That means you won't be able to filter using that field - the value is effectively null until the write happens on the server.

The timestamp estimation behavior you observe when you specify a SnapshotOptions only works when you have an actual DocumentSnapshot in hand. You can't filter on the estimated value of the timestamp.